This invention relates to an automatic liquid flow control device and more particularly to an automatic liquid flow control device for use in the application of building insulation foam comprised of resin and foaming agent. In applying insulating foam, air is mixed with the foaming agent at the applicator gun and then resin is applied to the mixture just prior to application. The proper ratio of resin to foaming agent is important. Too low a ratio produces a foam that is unsatisfactory for insulation and too high a ratio is inefficient, costly and environmentally injurious. Theoretically, a particular mixture of resin and foaming agent produces an optimum R value. The physical nature of the application systems and the materials involved do not allow an initial set mixture ratio to be maintained throughout the application as clogging and pumping variations will deviate the ratio beyond desired limits. To maintain the mixture ratio even within broad acceptable ranges, the mixture should be analyzed and the flow rate adjusted a number of times during application. Since this is laborious and time consuming, applicators tend to pour the resin too richly, thereby operating inefficiently, or they pour an inferior grade of insulating foam.
Prior to this device, applicant knows of no device available to provide selection of the mixture ratio of resin/foaming agent, the constant measurement and comparison of flow rates, and the constant adjustment of the flow rate of resin to maintain the ratio within acceptable efficient limits.